1. Technical Field
The present invention relates to a navigation server which supports guiding of a mobile subject by a navigation device, by transmitting a road traffic information to the navigation device possessed by the mobile subject.
2. Description of the Related Art
There is proposed a technique of promptly setting a detour route and informing the detour route and the like to a navigation device mounted on an automobile, when a disaster such as an earthquake or a flood occurred in an area, or when it is predicted that the disaster will occur in an area, so that the automobile traveling in that area may avoid the influence of the disaster (see Japanese Patent Laid-Open No. 2004-156941).
However, in the prior art mentioned above, a spot having high possibility of becoming an obstacle to the traveling of the automobile by the occurrence of the disaster is determined on the basis of a simulation or the like, and the detour route is set so as to avoid passing of the spot. Therefore, in the case where the simulation result deviates from the actual disaster condition, there is a possibility that the detour route which is inappropriate in consideration of the disaster condition may be set. For example, there is a possibility that a route unnecessarily detouring links having significantly low possibility of becoming an obstacle to the traveling of the automobile may be set. Further, in contrast thereto, there is a possibility that a detour route including a link having high possibility of becoming an obstacle to the traveling of the automobile will be set. Therefore, there is a fear that the user being informed of the detour route via the navigation device (car navigation) may be confused.